The following invention relates to a regrinding apparatus for a circular saw for sharpening each one of a plurality of teeth as each tooth is moved into engaqement with a pair of grinding wheels.
Circular saws for use in the wood products industry comprise a flat disc having a plurality of saw teeth. The saw teeth are usually in the form of carbide tips which are secured to tooth-shaped cutouts in the circular disc. Periodically the saw teeth need to be resharpened. Such saw teeth are usually resharpened one tooth at a time in a machine that advances the circular saw one tooth at a time into engagement with spinning, grinding wheels mounted side by side. The grinding wheels are usually diamond wheels which are hard enough to sharpen the carbide tips of the circular saw.
In the past such machines tended to be very costly because of the number of parts and the amount of steel needed to fabricate those parts. Such machines are often extremely heavy so that vibration does not impair the accuracy of the sharpening operation. An example of such a machine is a CSA200 dual side grinder available from Industrial Machine Company of Battleground, Wash. The CSA200 machine includes a pair of diamond grinding wheels mounted on spindles which are moved longitudinally along their axes into engagement with saw teeth one at a time as the teeth are advanced into enqagement with the wheels. The spindles are driven by motors connected thereto by belts and the motors are driven in unison with the spindles in the longitudinal direction. A motor mounting is provided for driving the motors along with the spindles along their longitudinal axes. Thus, in the CSA200 the motors are mounted on a track connected to the frame. A jack shaft, driven by a motor connected thereto by a sprocket and chain assembly, drives the motors along their respective tracks in unison with the spindles along their longitudinal axes. In this way the belts connecting the motor drive shafts to the spindles do not slip or get out of alignment. The drawback to this machine is that it is very expensive to include a large driving motor having sufficient torque to turn the jack shaft so as to move the spindle drive motors and the spindles at the same time. Since the motors are mounted on a track, the motor driving the jack shaft must overcome the friction of the heavy motors resting on the track. Additional expense is incurred in fabricating the tracks and linkages necessary to support the motors. In addition, means must be provided for maintaining proper tension on the belts. In the CSA200 this is provided by an adjustable spring-loaded rod that provides an upward bias on the spindles thus causing the belts to tighten.